This invention relates to aerodynamic deflection of air from the front of a vehicle and more particularly to an air dam apparatus for deflecting air from the front of a truck to prevent air from passing therebeneath, thus conducing to vehicle fuel savings.
The use of air deflectors for vehicles was proposed at least as long ago as 1936 in Backus U.S. Pat. No. 2,036,560 disclosing the use of an inverted airfoil at the front of a vehicle for streamlining purposes. Since then, there has been increasing usage of airfoils and so-called "wings" (so termed because of the airfoil configurations used), as well as spoilers at the front and rear of vehicles. Such devices have been used for two alternative purposes, primarily. These are increasing the "weight" or downforce of a vehicle upon its wheels for improving handling or traction; and decreasing aerodynamic drag.
Typical of the prior art concerned with the first purpose are Burst et al U.S. Pat. No. 3,869,166, disclosing a bulge-like, dipped extension around the front of an automobile at its lower margin; Swauger U.S. Pat. No. 3,618,998; and Holka et al U.S. Pat. No. 4,131,308. The latter two patents disclose so-called chin spoilers for vehicles, mounted to increasingly block or deflect air as air pressure in the spoiler increased with vehicle speed.
Typical of the prior art concerned with the second purpose is Heimburger U.S. Pat. No. 4,119,339. The latter discloses the use of a rectangular panel mounted by hinges at the lower edge of carryall-type vehicles and with a gear driven linkage mechanism for selectively raising or lowering the panel by swinging about the hinges.
The present invention is particularly concerned with the equippage of trucks, especially truck tractors of the type for hauling trailers at highway speeds, with an air deflector for reducing aerodynamic drag.
Such trucks, or truck tractors, and particularly the cab-over-engine (COE) design typically are blunt and large, having been developed to meet various laws and regulations and to provide maximum carrying capability but without concern for aerodynamics. The amount of air resistance, and consequent fuel economy, of such vehicles is dependent not only with the frontal area of the vehicle but also upon other factors including shape, surface texture, and various protrusions, apertures and other structure having high form drag or producing parasitic drag.
To improve aerodynamics of trucks and particularly COE tractors, wind deflectors have been used atop the cab roof whereby air will more smoothly flow up over the cab and any box-shaped trailer pulled by the tractor, said trailer often projecting well above the roofline of the tractor.
Although widespread usage of cab roof deflectors has been made, there can be disadvantages. Thus, where a tractor is used to pull a flatbed or tanker trailer, or is not pulling a trailer, the extra vertical protrusion of the deflector is counterproductive, adding only additional frontal area and consequently more form drag and thus causing poorer mileage than ordinarily. Thus, only tractors pulling high trailers can be advantageously equipped with a cab roof deflector.
It is believed that fuel savings estimated to be 5% can be obtained when such a cab roof deflector is used upon a tractor pulling such a high trailer. But, because of the high drag and general aerodynamic interference of air which is permitted to pass below the front bumper between the vehicle lower edge and ground level, and thus into what is herein termed a frontal clearance area of the vehicle, significant opportunity for fuel savings is lost. It is believed that fuel savings of about 3% may be obtained by deflecting air from such frontal clearance area in accordance with the invention regardless of what type of trailer, if any, the tractor is pulling. Accordingly, the accumulated total savings from apparatus of the invention can well exceed that obtained when using instead a cab roof deflector, considering the various types of trailer loads which a tractor may pull, as well as accessories when no trailer is being pulled.
However, a problem associated with "chin spoilers," airfoils and other devices proposed heretofore for deflecting air from the frontal clearance area of a vehicle is that the lower edge of the deflection apparatus has been required to be spaced well above ground level to allow for objects upon the ground, snow, ruts and other obstructions. Such spacing above ground allows air to pass beneath the deflector with consequent inefficiency. Proposals have been made, as in each of the above-identified Swauger, Holka et al and Heimburger patents to have the deflector swing down under highway travel conditions. But even when so deployed, the deflectors allow air to pass therebeneath, or are substantially unyielding to obstacles, or do not deflect air from the full width of the vehicle.
It is an object of the invention to provide an improved air dam apparatus for deflecting air from a frontal clearance area of a vehicle.
It is a further object of the invention to provide such an air dam apparatus particularly well-suited for use on trucks and truck tractors, etc., such is, for example, of the COE type.
It is a still further object of the invention to provide such an air dam apparatus which extends not only substantially down to ground level, but also across substantially the entire width of the vehicle, including in front of the tires.
It is another object of the invention to provide such an air dam apparatus which yields to road obstructions or hazards, such as objects, ruts, snow, etc. to prevent damage to the deflector yet returns to an air deflecting position after so yielding.
Among still other objects of the invention are the provision of such an air dam apparatus which is highly aerodynamically efficient; which is easily and quickly installed upon vehicles; which is of economical, long-lasting and simple construction, having a minimum of parts and components; and which provides an attractive appearance as a result of excellence of industrial design.
Various other objects and features will be in part apparent and in part pointed out hereinbelow.